UNDER option three, three alternative road user charging systems have been considered.

UNDER option three, three alternative road user charging systems have been considered.

The first is Distance-Based Road User Charging. This relates charges to distance travelled on roads suffering congestion at particular times. It relies on satellite positioning equipment in vehicles to track and charge for distance travelled by the vehicle and time at which the journey is made.

This scenario would result in limiting road vehicle congestion hours to 231,000, more than 23 per cent less than the results seen under the first option. While considered to be the most effective at tackling growing congestion, it relies on the introduction of technology to every vehicle - something that may not be realised for at least 15 years. Also relies on the implementation of schemes.

The second is a Zonal-Based System which identifies various areas and sets charges based on travel between them at specific times of the day and the levels of congestion. Such a system could be implemented before 2014 and could operate with a number of technologies working in parallel. This would be an interim step to distancebased charging.

The third is an A 9 Centre System which introduces a number of boundaries around the area's main commercial centres, the main congestion hotspots.

The technology needed to support this system would be similar to that seen in the Zonal-Based model. Although a system based on nine centre cordons would directly tackle the most congested areas, it would be liable to create unacceptable traffic diversions and "rat runs" through residential areas.

The report says while the impacts of the two area systems would not be as successful as under distance-based road user charging, they would significantly contribute to reducing congestion levels.